<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    p span {
      /* box-shadow: 2px 2px 5px red, -2px 2px 5px blue; */
      /* box-shadow: 2px 2px 5px 5px red; */
      /* box-shadow: 0px 0px 0px 0.01px red; */
      /* box-shadow: -1px 0px 0px red; */
      box-shadow: 1px 0px 0px red;
      /* border: 0.5px solid; */
    }
  </style>
</head>

<body>

  <p> this is <span>tag</span> p </p>
</body>

</html>